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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 560011
Title Role of interfacial elasticity for the rheological properties of saponin-stabilized emulsions
Author(s) Tsibranska, Sonya; Tcholakova, Slavka; Golemanov, Konstantin; Denkov, Nikolai; Pelan, Eddie; Stoyanov, Simeon D.
Source Journal of Colloid and Interface Science 564 (2020). - ISSN 0021-9797 - p. 264 - 275.
DOI https://doi.org/10.1016/j.jcis.2019.12.108
Department(s) Physical Chemistry and Soft Matter
VLAG
Publication type Refereed Article in a scientific journal
Publication year 2020
Keyword(s) Emulsion - Emulsion rheology - Interfacial rheology - Saponin - Surface elasticity - Surface rheology
Abstract

Hypothesis: Saponins are natural surfactants which can provide highly viscoelastic interfaces. This property can be used to quantify precisely the effect of interfacial dilatational elasticity on the various rheological properties of bulk emulsions. Experiments: We measured the interfacial dilatational elasticity of adsorption layers from four saponins (Quillaja, Escin, Berry, Tea) adsorbed on hexadecane-water and sunflower oil-water interfaces. In parallel, the rheological properties under steady and oscillatory shear deformations were measured for bulk emulsions, stabilized by the same saponins (oil volume fraction between 75 and 85%). Findings: Quillaja saponin and Berry saponin formed solid adsorption layers (shells) on the SFO-water interface. As a consequence, the respective emulsions contained non-spherical drops. For the other systems, the interfacial elasticities varied between 2 mN/m and 500 mN/m. We found that this interfacial elasticity has very significant impact on the emulsion shear elasticity, moderate effect on the dynamic yield stress, and no effect on the viscous stress of the respective steadily sheared emulsions. The last conclusion is not trivial, because the dilatational surface viscoelasticity is known to have strong impact on the viscous stress of steadily sheared foams. Mechanistic explanations of all observed effects are described.

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